1. Field of the Invention
The present invention relates to a gallium nitride (GaN)-based semiconductor laser device and a method for fabricating the GaN-based semiconductor laser device.
2. Related Background Art
Patent Literature 1 (Japanese Patent Application Laid-open No. 2010-129676) discloses a nitride semiconductor laser device with the emission wavelength of not less than 430 nm for characteristic improvements such as reduction of operating voltage, increase of external quantum efficiency, and reduction of lasing threshold current density. In this nitride semiconductor laser device, an n-type AlGaN cladding layer, a GaN layer, a first InGaN light guide layer, a light emitting layer, a second InGaN light guide layer, a nitride semiconductor intermediate layer, a p-type AlGaN layer, and a p-type AlGaN cladding layer are provided in this order on a nitride semiconductor substrate. The n-type AlGaN cladding layer has the aluminum (Al) composition of not less than 3% and not more than 5% and the thickness of not less than 1.8 μm and not more than 2.5 μm. Each of the first and second InGaN light guide layers has the indium (In) composition of not less than 3% and not more than 6%. The thickness of the first light guide layer is larger than that of the second light guide layer and is not less than 120 nm and not more than 160 nm. The p-type AlGaN layer is in contact with the p-type AlGaN cladding layer and has the aluminum (Al) composition higher than that of the p-type cladding layer and not less than 10% and not more than 35%.